Union Pacific Corp. could reach an agreement to acquire Norfolk Southern Corp. and create a transcontinental rail behemoth as soon as early next week, people familiar with the matter said.

Union Pacific , the largest U.S. railroad operator, could reach an agreement to acquire rival Norfolk Southern as soon as early next week, Bloomberg News reported on Friday, citing people familiar with the matter.

Norfolk stock traded as high as $288.11, but closed at $278, down 0.8%, while Union Pacific stock lost 4.5%, closing at $220.52. The S&P 500 added 0.1% and the Dow Jones Industrial Average lost 0.7%.